1. Field of the Invention
The present invention relates to a portable apparatus and a watch with a push button.
2. Description of the Prior Art
Some portable apparatus, including watches such as wristwatches and pocket watches, stopwatches, mobile phones, and personal digital assistants, have a push button that is attached to an enclosure body of the apparatus and activates a contact or the like therein. In a quartz watch, for example, pressing the push button can switch the time display from an analog form to a digital form, or allows correction of date and day displayed in a digital form.
Conventionally, to prevent accidental operation of the push button, portable apparatus of this type have a locking member having a female thread formed on the inner surface thereof, and the female thread engages a male thread formed on the outer surface of a pipe that is attached to the apparatus enclosure body. The locking member is configured to be movable between a locked position and an unlocked position by changing the position where these threads engage with each other. When the locking member is placed in the unlocked position, a stopper of the locking member is separated from a head of the push button passed through the pipe, allowing the push button to be pushed in with a travel corresponding to the separation distance. Conversely, when the locking member is placed in the locked position, the stopper comes into contact with the head of the push button, thereby preventing the push button from being pushed in.
The technique described in JP-A-2003-7164 does not have a feature for holding the locking member in the locked position. Therefore, even if biasing force of a coil spring that biases the push button acts on the locking member, vibration or impact on the apparatus when it is carried on the wearer's body could change the position where the locking member and the pipe engage with each other. Consequently, the locking member may slide from the locked position to the unlocked position when the apparatus is carried on the wearer's body and the function of preventing accidental operation of the push button may be defeated. Therefore, there is a desire to avoid such a situation.